Material working apparatus



y 1945- c. 1'. SOKOLOWSKY MATERIAL WORKING APPARATUS Filed May 27, 1944V: Y W w TS P Q mm 7 MA l0 55 I CY 5 Patented May 22, 1945 I MATERIALWORKING APPARATUS Charles '1. Sokolowsky, Cranlord, N. J., assignor toWestern Electric Company, Incorporated, New York, N. Y., a corporationof New York Application May 27, 1944, Serial No. 537,645

.6 Claims. (Cl. 164-118) This invention relates to material workingapparatus, and more particularly'to punch presses and material strippingmeans therefor.

In certain types of punch presses, after the blank or article is punchedfrom the material the latter is stripped from the punch by strippersactuatedby compression springs. In such instances stripper bolts areused for fixing the position of the stripper relative to the face of thepunch. In maintaining tools of this type, that is, the sharpening of thepunch and die, the stripper is usually dismantled, involving removal ofthe stripper bolts and springs. Furthermore, after each grinding of thepunch, similar variations must be made on the stripper bolts to maintainthe relationship of the stripper to the face of the punch, such as theforming of additional threads thereon. In tools of this type, thetension in the springs is usually fixed at a given value so as to applya given pressure to the material at the end of the downward travel ofthe punch, and to adapt the springs for compression thereof givendistances. However, as the punch is ground for sharpening and as thedistance between the stripper and the punch holder decreases, thetension in the spring may be increased until the safe stress in thespring is exceeded, so that when the tool is in use, the spring maybreak.

An object of the invention is to provide a material working apparatushaving a stripping means which is simple in structure, eflicient inoperation, and highly variable for variations in the punch associatedtherewith.

With this and other objects in view, the invention comprises a materialworking apparatus including a relatively movable punch and die, theformer carried by a punch holder which supports, through the aid ofstripper bolts, a stripper element, springs normally urging the elementtoward the die, and variable means disposed in the holder for supportingthe bolts and the stripper at varied positions relative to the punch.

Other objects and advantages will be apparent from the followingdetailed description when considered in conjunction with theaccompanying drawing, wherein Fig. 1 is a top plan view of theapparatus, and

Fig. 2 is a vertical sectional view taken substantially along the line2-2 of Fig. 1.

Referring now to the drawing, reference numeral l designates a punchholder having a shank II, which may be mounted in a reciprocable head ofa punch press (not shown). A punch i2 is removably mounted upon thepunch holder Ill by any suitable means (not shown). The punch l2cooperates with a die It, during the operation of the press, to punchportions or articles from a material l5, the die having an aperture l6therein conforming to the cross-sectional contour of the punch l2. Thedie It is mounted upon a die shoe H in any suitable manner (not shown),the latter having flanges i8 thereon for use in mounting on the punchpress (not shown).

A stripper element 20 is, in the present embodiment, centrallyapertured, as at 2i, to receive the punch 12 and to move relative to thepunch during the punching operation. In the present embodiment there arefour stripper bolts 22, which have their lower ends threadedlyconnected, as at 23, with the stripper element 20. The upper ends of thebolts, including their heads 24, are disposed in cup-shaped supportingelements or sleeves 25 of the cross-sectional contour illustrated inFig. 2. Compression springs 26 are disposed concentric with theirrespective stripper bolts 22 between the stripper element 20 and theirrespective sleeves 25. The bolts 22 are free to move in apertures 28 inthe bottom walls of the sleeves 25, these walls or portions of thesleeves functioning in cooperation with the heads 24 to limit thedownward movement of the bolts 22 to position the element 20 relative tothe punch I2. The sleeves 25 are externally threaded and are disposed inthreaded apertures 30 of the punch holder i0, tool receiving slotsSI-being formed in the upper edges of the sleeves so that, through theaid of a suitable tool, the sleeves may be adjusted vertically.

Means is provided to lock each of the sleeves 25 in any desired adjustedposition. This means includes rods 33, which are formed of suitablematerial, preferably brass, and are provided with thread portions 34 intheir inner ends to conform to the adjacent threads of their apertures30. The rods 33 are disposed in apertures 35 and are engaged by setscrews 36 threadedly disposed in the punch holder in alignment withtheir respective rods to serve in forcing the rods into intimateengagement with their respective sleeves 25.

Considering now the operation of the apparatus, let it be assumed thatthe die I is disposed at a fixed position and that the punch isreciprocated through repeated cycles during intermittent advancement ofthe material ii. In following one complete cycle of the apparatus,starting with the punch in the upper position and the material I5advanced, the punch holder 10 with the punch l2 and the strippingmechanism are moved downwardly a sufllcient distance for the stripperelement 20 to first engage the material and cooperate with the die inholding the material against displacement, immediately after which thepunch cooperates with the die in punching a portion or article from thematerial.

This completes one half of the operating cycle;

The upper structure is then moved upwardly, first removing the punchfrom the die, the force of the springs 26 on the stripper element 20functioning to hold the material [5 until the punch has been removedtherefrom, after which the heads 24 of the stripper bolts will beengaged by the sleeves 25 to raise the stripper element upwardly withthe punch. This operation continues, but eventually the punch will needto be reconditioned, that is, sharpened by a grind ing operation.

In other structures of this type, it is necessary that the stripperplate, together with the stripper bolts and springs supporting it, beremoved from the punch to allow sufllcient room about the punch for thegrinding wheel during the grinding or reconditioning process. In thepresent embodiment this is not necessary. To condition the punch forgrinding, the set screws 36 are loosened, to remove the holding force oftheir rods 33 upon their associated sleeves 25. The sleeves 25 are thenrotated in their threaded aperture, to draw the stripper elementupwardly on the punch to expose a sufllcient portion of the working endof the punch for the grinding operation.

After the completion of the grinding operation, the stripper element 20and its associated parts, which have retained their connection with thepunch holder, may be moved downwardly or toward the working end of thepunch to locate the element in its new position. A new position isrequired for the stripping element due to the fact that a portion of thematerial at the working end of the punch has been removed during thegrinding operation. Thus it is possible to locate the stripping elementat a new position through the aid of the sleeves 25 in their threadedapertures. When this has been accomplished, the rods 33 are forced intointimate engagement with their sleeves 25 through the aid of the setscrews 36 and the apparatus is again in condition for use. During thisreconditioning process, all of the parts have been retained in assembly,eliminating any possibility of loss of or damage to any of these parts,which might occur if they should be removed entirely from the punchholder and separately laid to one side. Furthermore, due to themaintaining of the various parts in assembly, the time required torecondition the punch is reduced considerably. One of the mainadvantages, however, lies in the fact that wide and numerous variationsmay be made in the position of the stripper element relative to thepunch without varying the associated springs or the desired tensions orforces created therein. Furthermore, if desired the entire strippermechanism may be removed from the punch and punch holder withoutseparating any of the parts therefrom. This is due to the fact that itis not necessary toremove the bolts 22 from the stripper element, anddue to their holder and punch, the springs in the stripping mechanismmaintain their uniform tension throughout the life of the punch, thisbeing of great importance in the accurate production of the work,particularly the production of numerous like parts from the materialwithout variations which might result from variations in the tension ofthe springs or the force of the stripper element.

Although specific improvements of the invention have been shown anddescribed, it will be understood that they are but illustrative and thatvarious modifications may be made therein without departing from thescope and spirit of this invention as defined by the appended claims.

What is claimed is:

1. In a material working apparatus, a punch, a holder therefor, astripper element movable relative to the punch from a normal position, aspring to normally apply a. given force to the stripper element to urgeit toward its normal position, a reciprocal member secured to the stripr element, a support for the member carried by the holder and movablerelative thereto to vary the position of the element relative to thepunch free of causing any variations in the force of the spring, amember laterally movable in the holder, and means to move the memberinto intimate engagement with the support to lock the support in anydesired position relative to the holder.

2. In a material working apparatus, a punch, a holder therefor having athreaded aperture therein, a stripper element movable relative to thepunch from a normal position, a spring to normally apply a given forceto the stripper element to urge it toward its normal position, areciprocal member having a reduced threaded end disposed in a threadedaperture of the stripper element and a shoulder resting thereon, and

a threaded support for the member movable in the threaded aperture tovary the normal position of the element and maintain the said givenforce of the spring.

3. In a material working apparatus, a punch, a holder therefor having athreaded aperture therein, a stripper element movable relative to thepunch from a normal position, a spring to normally apply a given forceto the stripper element to urge it toward its normal position, areciprocal member secured to the stripper element, a threaded supportfor the member movable in the threaded aperture to vary the normalposition of the element and maintain the said given force of the spring,and a pin carried by the holder and movable into engagement with thesupport to lock the support in any selected position in the aperture.

4. In a material working apparatus, a punch, a holder therefor havingspaced threaded apertures therein, and a stripper unit including astripper element, reciprocable members having reduced threaded endsdisposed in threadedapertures of the stripper element and adjacentshoulders resting thereon, springs disposed on the stripper elementconcentric with the members, and threaded supports for the membersreceivable in the said threaded apertures and movable therein to locatethe stripper element at any desired position relative to the punch.

5. In a materal working apparatus, a punch, a holder therefor havingspaced threaded apertures therein, reciprocable members secured atspaced positions to the stripper element, springs disposed on thestripper element concentric with the members, threaded supports for themembers receivable inthe said threaded apertures and movable therein tolocate the stripper element at any desired position relative to the forthe members receivable in the threaded apertures for connection of theunit to the holder and for normally positioning the stripper element atany desired location relative to the punch and cooperating with theelement to maintain a given normal force in each spring, and meansformed for interflt'ting engagement with each of the threaded supportsto lock it in any desired location.

- CHARLES T. SOKOLOWSKY.

